Items you will need
Large sheet cake
Icing bags with a star tip and round tip
Most little boys love anything with wheels, including tractors. If you are looking for a cake design for your son's birthday party, consider this tractor cake. All you need is a sheet cake and a lot of icing. Since tractors aren't that complicated, you won't need a lot of artistic talent to make one, although it is helpful.
Buy a large sheet cake or make one yourself. If you make one yourself, wait until it cools off before you decorate it.
Draw the outline of a tractor on your sheet cake with some icing. Reference the photo above for a general idea of the shape.
Use a knife to cut around the cake where you drew the outline. Go slowly so that the lines are smooth. Put the left over cake aside.
Place one color icing in each icing bag. If you don't have the right color just add some food coloring to white icing and mix thoroughly.
Use a round tip to make all of the outlines of your cake (again, reference photo for basic shape). Black icing should be used to do the outline. Outline the whole tractor, the tires, the windshield, the side window, front bumper, mouth near the bumper, and eyes in the windshield. You don't have to give it eyes or a mouth--that is optional. If you do go with the eyes and mouth, make it look like a happy character.
Use a star tip to fill in the cake. The main part of the tractor should be green. The inside of the tires should be yellow and the outside black. Make the mouth red.
Make the eyes white with blue on the inside. Add the black pupils.
Fill in the rest of the windshields, tires, and bumper with black icing.
Use the leftover icing on the leftover cake and eat that as a treat before your guests arrive. No two cakes have to look the same. If you want to make your mouth a simple line, go ahead. If you want to make it a filled in character mouth, you can do that too.
Don't try to make the cake without first doing the outlines. Things could end up lopsided or the wrong size.